1. Field of the Invention
The present invention relates to a cooling system for use in connection with an electrical circuit board. More specifically, the invention involves a method and apparatus for cooling an electrical device attached to a printed circuit board by providing a thermal conduit from the device to a heat sink. The electrical circuit board cooling system has particular utility in connection with multi-layer board configurations where the heat generated by a device must be conducted to a heat sink located to the side of a printed circuit board.
2. Description of Related Information
It is common to use a beat dissipation device, such as a heat sink, for thermal cooling purposes in a circuit assembly. Traditionally, heat sinks are placed in direct contact with a device to prevent device overheating. A device is attached to a heat sink using a multiplicity of fasteners. The fasteners lengthen assembly time. Additionally, using one heat sink for each device adds to the space required by the board layout.
The problems of individual component heat sinks have been overcome by placing the entire board on a cooling surface such as a thermal pad. The thermal pad, or cold plate, acts as a heat sink, and individual components are on top of the board and heat dissipation paths go through the board to the pad, which is on the underside of the board. Multiple devices can share a single thermal pad, and connecting the devices to the thermal pad conserves space and assembly time.
The design space for electrical components is shrinking. As goods become smaller, more components are squeezed into a decreasing amount of space. The space required by thermal pads becomes relevant and, particularly as boards are mounted close to other boards, the thermal pad of one board may generate heat that affects other components. Although the boards may be oriented differently, so that a component "sandwich" is formed, this formation makes multiple thermal pads a necessity.
To meet space requirements and overcome other drawbacks of multiple heat sinks or pads, a need exists for a simple and inexpensive method and apparatus that can minimize thermal dissipation device space requirements in a design where circuit boards are stacked or otherwise placed in close proximity to one another.